Purification and characterization of sulfur reductase from a moderately thermophilic bacterial strain, TI-1, that oxidizes Iron

Tsuyoshi Sugio, Keiichi Oda, Keiko Matsumoto, Masaki Takai, Satoshi Wakasa, Kazuo Kamimura

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A moderately thermophilic bacterium, strain TI-1, produces H2S outside of the cells when grown at 45°C on Fe2+-medium (pH 1.8) containing elemental sulfur and L-glutamic acid. A newly identified sulfur reductase was present in the cytosol of this strain and was purified to an electrophoretically homogeneous state from strain TI-1. The apparent molecular weight of sulfur reductase was 86,000 by gel filtration and 48,000 by SDS-PAGE, so the enzyme was a homodimer. The enzyme was most active at pH 9.0 and 60 to 70°C, and it catalyzed the reduction of 1 mol of elemental sulfur with 1 mol of NADH to give 1 mol of H2S and 1 mol of NAD+. Elemental sulfur was a specific electron acceptor of this enzyme. Thiosulfate, sulfite, and tetrathionate were not electron acceptors, but inhibited sulfur reductase activity. NADPH was not used as an electron donor.

Original languageEnglish
Pages (from-to)705-709
Number of pages5
JournalBioscience, Biotechnology and Biochemistry
Issue number4
Publication statusPublished - Jan 1 1998



  • Hydrogen sulfide
  • Iron-oxidizing bacterium
  • Moderate thermophile
  • Sulfur reductase

ASJC Scopus subject areas

  • Biotechnology
  • Analytical Chemistry
  • Biochemistry
  • Applied Microbiology and Biotechnology
  • Molecular Biology
  • Organic Chemistry

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